Novel 2-hydroxynaphthalene-1-aldehydes, process for preparing them and their use

ABSTRACT

Novel 2-hydroxynaphthalene-1-aldehydes have been found which have the general formula (I) ##STR1## wherein R is a carboxylic acid group, a carboxylic acid ester group, preferably of an alkanol or of an optionally substituted phenol, an optionally substituted carboxylic acid amide group, or an optionally substituted carboxylic acid hydrazide group, which are very valuable intermediate products for the preparation of coloring agents, optical brighteners, textile auxiliary agents and pharmaceutical products.

The present invention relates to novel 2-hydroxynaphthalene-1-aldehydes,to a process for preparing them and their use.

Novel 2-hydroxynaphthalene-1-aldehydes have been found which have thegeneral formula (I) ##STR2## wherein R is a carboxylic acid group, acarboxylic acid ester group, preferably of an alkanol or of anoptionally substituted phenol, an optionally substituted carboxylic acidamide group, or an optionally substituted carboxylic acid hydrazidegroup.

Carboxylic acid alkyl ester groups are preferably those having from 1 to5 carbon atoms in the alkyl radical which may be straight-chained orbranched or substituted, for example by phenyl or by a phenyl radicalsubstituted by one or more, preferably 1, 2 or 3 substituents selectedfrom the group of chlorine, fluorine, bromine, methyl, ethyl, methoxy,ethoxy, trifluoromethyl, nitro, acetylamino, cyano and carboxylic acidphenyl ester, in which the phenyl radical may be substituted by one ormore, preferably 1, 2 or 3 substituents selected from chlorine, bromine,fluorine, methyl, ethyl, methoxy, ethoxy, trifluoromethyl, nitro,acetylamino and cyano.

Substituted carboxylic acid amide radicals are in particular those whichcontain at the N-atom 1 or 2 alkyl radicals, especially those havingfrom 1 to 4 carbon atoms, which may be further substituted, or containone aryl radical, such as for example a phenyl radical or a naphthylradical which may be substituted, or those which contain one of theabove-mentioned alkyl radicals and one aryl radical each bound at thenitrogen atom. Of these, there are to be mentioned in particularcarboxylic acid amide groups which have the formula ##STR3## in which R₁stands for hydrogen, an alkyl group having from 1 to 4 carbon atomswhich may be substituted by lower alkoxy, such as methoxy and/or ethoxy,or by hydroxy or halogen, especially chlorine or bromine, R₂ has themeaning of R or represents a phenyl radical optionally substituted byone or more, preferably 1, 2 or 3 substituents selected from the groupconsisting of fluorine, chlorine, bromine, methyl, ethyl, methoxy,ethoxy, trifluoromethyl, nitro or cyano, or is the benzyl or phenethylradical.

Substituted carboxylic acid hydrazides are particularly those whichcontain an aryl radical at the nitrogen atom in the β-position and/or analkyl radical at the nitrogen atom in the α- and/or β-position. Ofthese, there are to be mentioned, besides the carboxylic acid hydrazidegroup itself, those carboxylic acid hydrazide radicals which have theformula ##STR4## in which R₁ is defined as above, R₄ is different fromR₁ or is identical with it and has the meaning of R₁, and R₃ stands foran alkyl radical having from 1 to 4 carbon atoms, or for the benzyl orphenethyl radical or for a naphthyl or phenyl radical, each of which maybe substituted in the benzene nucleus by one or several, preferably 1, 2or 3 substituents selected from the group consisting of fluorine,chlorine, bromine, methyl, ethyl, methoxy, ethoxy, trifluoromethyl,nitro, acetylamino and cyano, in which case at least one of the threesubstituents R₁, R₃ and R₄ is no hydrogen atom.

The novel 2-hydroxynaphthalene-1-aldehydes can be prepared according tothe invention by a process which comprises reacting a2-hydroxynaphthalene of the formula (II) ##STR5## in which R is definedas above, with hexamethylene-tetramine, in the presence of an optionallyhalogenated, for example chlorinated, lower aliphatic mono- ordicarboxylic acid.

The 2-hydroxynaphthalenes of the formula (II) used as starting compoundsmay be obtained by carboxylation of 2-hydroxynaphthalene-potassium (cf.German Patent Specification No. 436 524) and, optionally, by asubsequent conversion of the 2-hydroxynaphthalene-6-carboxylic acid thusobtained into the esters, amides or hydrazides thereof.

The process is preferably carried out in such a manner that the startingcompound of the formula (II) and hexamethylene-tetramine are dissolvedor suspended in generally two to ten times the amount of aliphaticcarboxylic acid and are heated for a longer period of time at atemperature of up to 120° C, preferably in the range of from 80° to 100°C, in which process the addition of a small amount of mineral acid, suchas sulfuric acid or hydrochloric acid, is required, except for areaction wherein trifluoroacetic acid is used as a halogenated aliphaticacid. The acid may be added directly in admixture with the carboxylicacid, or may be added subsequently.

As lower carboxylic acids there are suitable for the reaction inparticular acetic acid, but also propionic acid, butyric acid or valericacid, moreover, dicarboxylic acids, such as adipic acid or malonic acid,or halogenated fatty acids, such as chloroacetic acid, trichloro-aceticacid or trifluoro-acetic acid.

Hexamethylene-tetramine may also be replaced by a mixture of ammonia andformaldehyde having an analogous effect, in which process ammonia andformaldehyde may be used in an aqueous solution or in the gaseous state.

The hexamethylene-tetramine is used in a stoichiometrical amount or in asmall excess amount. In addition to that, also paraformaldehyde in amolar ratio of from 1:1 to 3:1, calculated on the starting compound ofthe formula (II), can be used.

The 2-hydroxynaphthalene-1-aldehydes of the invention are valuableintermediate products for the preparation of dye-stuffs, opticalbrighteners, textile auxiliary agents and pharmaceutical compounds. Theyare particularly suitable for the preparation of azomethine dyes whichare obtained by the condensation of these aldehydes with suitableamines.

Thus, they yield for example, by the condensation of 1 mole of thealdehyde with 1 mole of an isocyclic or heterocyclic monoamine,compounds of the formula ##STR6## wherein R is defined as above and Arepresents an isocyclic or heterocyclic radical, which are suitable ascoloring agents; by the condensation of 2 moles of aldehyde (I) with 1mole of hydrazine or of an aliphatic, isocyclic or heterocyclic diamine,compounds were also obtained in an analogous manner which are suitableas dyeing agents having very good properties and which correspond to theformula ##STR7## in which R is defined as above and B represents asingle bond, a straight-chain or branched alkylene radical possiblyinterrupted by hetero atoms, a bivalent group and/or an isocyclic ring,or represents a cycloalkylene radical, an arylene or a heterocyclicradical, or corresponding metal complex compounds are obtained bysubsequent metallization.

The mono- an disazomethine compounds which can thus be obtained from thenovel naphthaldehyde (I), are suitable for the pigmentation of printingpastes, of high-molecular-weight plastic compositions or lacquers, andin this respect they show better fastness properties with regard tosolvents and more pure colour shades than the known isomeric dyestuffsprepared from those aldehydes which show the grouping R in the3-position (cf. French Patent Specification No. 1,503,786 and1,449,666).

Furthermore they yield lacquer coatings having a very good fastness tocross-lacquering, and possess a good fastness to bleeding in plasticizedpolyvinylchloride.

Those compounds of the formula (I), in which R represents the carboxygroup, a carboxylic acid-alkylester radical having from 1 to 4 carbonatoms in the alkyl group, the carboxylic acid amide group, a carboxylicacid-mono-(C₁ -C₄ -alkyl)-amide group, a carboxylic acid-di-(C₁ -C₄-alkyl)-amide group, the carboxylic acid-phenylamide or the carboxylicacid-phenylhydrazide group, as well as the naphthaldehyde compounds ofthe Examples 1, 3, 4, 5 and 6 are of particular interest.

The following Examples serve to illustrate the invention; the partsbeing parts by weight.

EXAMPLE 1

3 Parts of paraformaldehyde, 18.8 parts of2-hydroxynaphthalene-6-carboxylic acid and 14 parts ofhexamethylenetetramine (urotropine) were introduced one after the otherinto 35 parts of glacial acetic acid at room temperature, while stirringthoroughly. The reaction mixture was subsequently heated for 3 hours at80° C. After 75 parts of glacial acetic acid and a mixture of 9 parts ofwater and 15 parts of sulfuric acid of 95% strength had been added, themixture was heated for another 5 hours at 80° C. Subsequently 75 partsof hot water were added, and the reaction mixture was cooled. Theprecipitate was filtered off with suction and was washed with warm wateruntil neutral. After drying, 17 parts of the aldehyde of the formula##STR8## where obtained, which had a melting point of 309° C.

Analysis: C₁₂ H₈ O₄ Calc. C 66.6%: H 3.7%: Found C 66.8%: H 3.7%.

Molar mass: 216 (mass spectrum).

Phenylhydrazone: melting point 288° C

Molar mass: 306 (mass spectrum).

EXAMPLE 2

18.8 Parts of 2-hydroxynaphthalene-6-carboxylic acid, 20 parts ofhexamethylene-tetramine and 5 parts of paraformaldehyde were introducedinto 180 parts of glacial acetic acid, while stirring. Subsequently 40parts of concentrated hydrochloric acid were slowly added dropwise, andthe mixture was heated for 1 hour at a temperature in the range of from90° to 100° C. After 40 parts of concentrated hydrochloric acid hadagain been added, the reaction mixture was heated once more for 1 hourat a temperature of from 90° to 100° C. Subsequently 150 parts of hotwater were added, and the mixture was allowed to cool. The precipitatewas filtered off and was washed with warm water until neutral. Afterdrying, 15 parts of an aldehyde were obtained, which was identical withthe one obtained according to Example 1.

EXAMPLE 3

If in Example 1 the 2-hydroxy-naphthalene-6-carboxylic acid was replacedby 18.7 parts of 2-hydroxy-naphthalenecarboxylic acid-amide, 16.3 partsof the aldehyde of the formula ##STR9## were obtained, which had amelting point of 285° C.

Analysis: C₁₂ H₉ NO₃ Calc. C 67.0%: H 4.2%: N 6.5%: Found C 66.7%: H4.2%: N 6.3%.

Molar mass: 215 (mass spectrum).

EXAMPLE 4

If in Example 1 the 2-hydroxy-naphthalene-6-carboxylic acid was replacedby 26.3 parts of 2-hydroxy-naphthalene-6-carboxylic acid anilide, 25parts of the aldehyde of the formula ##STR10## were obtained, which hada melting point of 308° C.

Analysis: C₁₈ H₁₃ NO₃ Calc. C 74.2%: H 4.5%: N 4.8%: Found C 74.5%: H4.3%: N 5.0%.

Molar mass: 291 (mass spectrum).

EXAMPLE 5

If in Example 1 the 2-hydroxy-naphthalene-6-carboxylic acid was replacedby 20.2 parts of 2-hydroxy-naphthalene-6-carboxylic acid-methylester,17.4 parts of the aldehyde of the formula ##STR11## were obtained, whichhad a melting point of 205° C.

Molar mass: 230 (mass spectrum).

In an analogous manner, the following aldehydes of the formula I wereobtained:

    ______________________________________                                                                Molar mass  Melting                                   Ex.   R                 (mass spectrum)                                                                           point                                     ______________________________________                                        6     COOCH.sub.2 CH.sub.2 CH.sub.2 CH.sub.3                                                          272         83° C                              7     CONHCH.sub.3                                                            8     CONHCH.sub.2 CH.sub.2 CH.sub.2 CH.sub.3                                 9     CON(C.sub.4 H.sub.9).sub.2                                              10                                                                                   ##STR12##                                                              11                                                                                   ##STR13##                                                              ______________________________________                                    

EXAMPLE 12

14.9 Parts of 5-aminobenzimidazolone as well as 21.6 parts of1-formyl-2-hydroxy-naphthalene-6-carboxylic acid were introduced, whilestirring, at room temperature into a mixture of 130 parts of ethanol and20 parts of glacial acetic acid. Subsequently the mixture was heated atboiling point for 3 hours. The residue was suction-filtered, while stillhot, and was washed well with ethanol. The moist product was heated to100° C in 80 parts of dimethylformamide, was again suction-filtered,while hot, and washed once more thoroughly with ethanol. After drying,32.1 parts of a bright yellow dyestuff of the formula ##STR14## wereobtained, which dyed polyvinyl chloride in clear yellow shades withexcellent fastness properties.

EXAMPLE 13

If in Example 12 the 1-formyl-2-hydroxy-naphthalene-6-carboxylic acidwas replaced by 21.5 parts of the aldehyde described in Example 3, 28parts of a yellow azomethine pigment were obtained, which had theformula ##STR15## A lacquer which was pigmented with this compoundyielded yellow lacquer coatings having a good fastness to light and tocross lacquering.

If in Example 12 the 5-amino-benzimidazolone was replaced by the aminesindicated in Table 1 below, the corresponding azomethine compounds wereobtained having very good pigment properties as to the fastness to lightand over-varnishing.

                  Table 1                                                         ______________________________________                                                                  Color shade of the                                  Example                                                                              Amine              azomethine compound                                 ______________________________________                                        14                                                                                    ##STR16##         yellow                                              15                                                                                    ##STR17##         yellow                                              16                                                                                    ##STR18##         orange                                              17                                                                                    ##STR19##         red                                                 18                                                                                    ##STR20##         orange                                              ______________________________________                                    

EXAMPLE 19

A mixture of 21.6 parts of 6-carboxy-2-hydroxy-1-naphthaldehyde, 36.6parts of 6'-aminobenzimidazolonyl-azo-5'-acetoacetic acid-4-toluidideand 700 parts of water was ground at the pump-over device by means of acorundum disk attrition mill for 30 minutes under a nitrogen atmosphere.The suspension obtained was passed with the exclusion of oxygen into aflask, and the condensation was carried out within 6 hours, whilestirring and increasing the reaction temperature steadily from 30° to100° C. In order to avoid any secondary reactions, a slight inert gascurrent was passed through the suspension during this time. After aninternal temperature of 100° C had been reached, the mixture wascontinued to be stirred for 30 minutes, then it was filtered off withsuction while hot, and was washed with hot water and dried at 80° C inthe circulating air cabinet.

56.3 Parts of an orange-colored pigment having the formula ##STR21##were obtained in a quantitative yield. The pigment could be usedexcellently for the preparation of dyeings of plastic materials andparticularly of paints and lacquers, due to its high tinctorial strengthand its good fastness to solvents and to light.

EXAMPLE 20

21.6 Parts of 1-formyl-2-hydroxy-6-naphthoic acid were added whilesitrring to 3.0 parts of 1,2-diaminoethane dissolved in 250 parts ofethanol and 10 parts of glacial acetic acid, and the mixture was heatedfor 3 hours at boiling point. After cooling, the yellow compound wassuction-filtered and washed thoroughly with ethanol. The moist productwas then introduced into 150 parts of dimethylformamide, was mixed with9.0 parts of nickel diacetate and heated for 4 hours at 120° C. Theyellow pigment thus obtained was filered off with suction while hot andwas washed thoroughly first with hot water and subsequently withethanol. After drying, 30.2 parts of a yellow pigment were obtained,which had the formula ##STR22## Ni: calculated 11.4%; found 11.3%, andwhich dyed polyvinyl chloride in a clear yellow shade having excellentfastness properties.

EXAMPLE 21

21.6 Parts of 1-formyl-2-hydroxy-6-naphthoic acid, 3.0 parts ofdiaminoethane and 9.0 parts of nickel diacetate were heated in 300 partsof ethanol at boiling point for 5 hours. The yellow compound wasfiltered off with suction while hot and was washed thoroughly with hotwater and ethanol. The product was then heated in 150 parts ofdimethylformamide for 1 hour at 120° C, was filtered off while hot, andwas washed thoroughly with hot water and ethanol. After drying, 31.0parts of a yellow pigment were obtained, which was identical with theone obtained according to Example 20.

EXAMPLE 22

10.8 Parts of 1-formyl-2-hydroxy-6-naphthoic acid were introduced, whilestirring, into 5.5 parts of 2-aminophenol in 100 parts of ethanol and 10parts of glacial acetic acid, and the mixture was heated at the boilingpoint for 3 hours. After cooling, the yellow compound was filtered off,was washed thoroughly with ethanol and was then introduced once moreinto 100 parts of ethanol. Subsequently, 10.0 parts of copper acetatewere added, and the whole was heated for 5 hours at boiling point. Thecompound formed was filtered off at 40° C and was washed with hot waterand ethanol. After drying, 13.2 parts of a yellow-green pigment wereobtained, which had the formula ##STR23## Cu: calculated 17.2%; found17.0%, and which permitted the preparation of lacquers having a metaleffect and showing a good fastness to light and to cross-lacquering.

EXAMPLE 23

5.5 Parts of 2-aminophenol were added, while stirring, to 10.8parts of1-formyl-2-hydroxy-6-naphthoic acid and 10.0 parts of copper acetate in100 parts of ethanol. Subsequently the mixture was heated for 6 hours atboiling point. The complex compound was filtered off at 40° C and waswashed with hot water and alcohol. After drying, 12.5 parts of ayellow-green pigment were obtained, which was identical with the oneprepared according to Example 22.

We claim:
 1. A compound of the formula ##STR24## in which R is carboxyor carboxylic acid-alkylester of from 1 to 4 carbon atoms in the alkylgroup.
 2. The compound of the formula of claim 1 in which R is carboxy.3. The compound of the formula of claim 1 in which R is carboxylicacid-methylester.
 4. The compound of the formula of claim 1 in which Ris carboxylic acid-n-butylester.